Enter World 7-8 with a Tanooki Suit. Go down the pipe that leads to the room containing the giant Question Block, then hit it to release a Hammer Suit. Stand in a place where you think the Hammer Suit will bounce on you, and press Down and B to turn into a statue. If you get the Hammer Suit while you're in statue form, you'll transform into a gray Hammer Mario! The bad thing about this cool bug is that you can't go up the exit pipe; you're stuck in the secret room until time runs out.